`
`United States Patent
`
`
`Hurwitt et a1.
`
`
`[191
`
`
`llllllllllllllllllllllllllllllll|||||IllllIllll|||||Illllllllllllllllllllll
`USOOSl30005A
`
`
`
`
`
`5,130,005
`[11] Patent Number:
`
`
`
`
`
`
`Date of Patent:
`{45]
`Jul. 14, 1992
`
`.
`
`
`[54]
`
`
`[75]
`
`
`[73]
`
`
`[21]
`
`[221
`
`
`[63]
`
`
`[51]
`[52]
`
`
`
`[58]
`
`MAGNETRON SPU’I'I'ER COATING
`
`
`
`METHOD AND APPARATUS WITH
`
`
`
`
`ROTATING MAGNET CATHODE
`
`
`
`
`
`
`
`
`
`Inventors: Steven Hurwitt, Park Ridge, N.J.;
`
`
`
`
`Robert Hieronymi, Rock Cavern;
`
`
`
`
`
`Israel Wagner, Monsey, both of NY.
`
`
`
`
`Assignee: Materials Research Corporation,
`
`
`Orangeburg, N.Y.
`
`
`
`App]. No.: 626,987
`Filed:
`Dec. 13, 1990
`
`
`
`
`
`Related U.S. Application Data
`
`
`
`
`
`
`
`
`
`
`
`Continuation-impart of Ser. No. 606.701, Oct. 31, 1990,
`abandoned, which is a continuation-in-part of Ser. No.
`
`
`
`
`
`$70,943, Aug. 22, 1990, which is a continuation-in-part
`
`
`
`
`
`of Ser. No. 339,308, Apr. 17, 1989, Pat. No. 4,957,605.
`
`
`
`
`
`
`
`
`
`
`Int. Cl.5 .............................................. C23C 14/35
`
`
`
`
`
`U.S. Cl. ............................ 204/192.12; 204/298.2;
`
`
`
`
`204/298.09
`
`Field of Search ...................... 204/ 192.12, 298.09,
`
`
`
`
`
`204/2982
`
`
`
`[56]
`
`References Cited
`
`
`U.S. PATENT DOCUMENTS
`
`
`
`3,393,142 7/1968 Moseson ......................... 204/298.06
`
`
`
`
`
`5/1976 McLeod ......
`3,956,093
`204/192.12
`
`
`
`
`
`
`
`4,162,954 7/1979 Morrison, Jr.
`..
`204/298.l9
`
`
`
`
`
`
`4,180,450 12/1979 Morrison, Jr.
`..
`204/298.19
`
`
`
`
`
`
`204/298.19
`4,239,611 12/1980 Morrison, Jr.
`..
`
`
`
`
`
`204/298.19
`5/1981 Morrison, Jr.
`..
`4,265,729
`
`
`
`
`
`
`204/192.l3
`4,401,539
`8/1983 Abe et a1.
`
`
`
`
`
`
`4,444,643 4/1984 Garrett .............. 204/2982
`
`
`
`
`
`
`.....
`4,461,688 7/1984 Morrison, Jr.
`204/192.l2
`
`
`
`
`
`
`
`
`4,498,969 2/1985 Ramachandran ..
`204/192.12
`
`
`
`
`
`
`4,525,264
`6/1985 Hoffman .............
`, 204/29822
`
`
`
`
`
`4,631,106 12/1986 Nakazato et a1.
`..
`..... 156/345
`
`
`
`
`
`
`4,714,536 12/1987 Freeman et a1.
`.......
`.. 204/2982
`
`
`
`
`
`
`
`5/1988 Ferenbach ct a].
`...... 204/298.2
`4,746,417
`
`
`
`
`
`
`
`4,761,219
`8/1988 Sasaki et a1.
`...........
`204/298.37
`
`
`
`
`
`
`
`4,793,911 12/1988 Kemmerer et al.
`204/29827
`
`
`
`
`
`
`1/1990 Welty .................
`4,892,633
`204/192.12
`
`
`
`
`
`
`7/1990 Kakehi et a1.
`.................. 204/192.32
`4,943,361
`
`
`
`
`
`
`
`
`
`
`
`
`
`4,995,958
`2/1991 Anderson etal. ............... 204/2982
`
`
`
`
`
`
`6/1991 Bonyhard etal. ............. 204/298.16
`5,026,470
`
`
`
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`
`
`0054201
`6/1982 European Pat. Off.
`....... 204/298.37
`
`
`
`
`
`
`
`0211412 7/1986 European Pat. Off.
`204/298.2
`..
`
`
`
`
`
`
`
`
`
`0334347
`3/1989 European Pat. Off.
`204/298.2
`..
`
`
`
`
`
`
`
`
`0365249 10/1989 European Pat. Off.
`204/298.2
`..
`
`
`
`
`
`
`
`2707144
`8/1977 Fed. Rep. of Germany
`204/2982
`
`
`
`
`
`
`
`59—215484 12/1984 Japan ................................ 204/2982
`
`
`
`
`
`
`
`
`
`
`
`61-29197] 12/1986 Japan .....
`204/2982
`63-149374 6/1988 Japan .....
`....204/2982
`
`
`
`
`
`63-290275 11/1988 Japan .....
`204/2982
`
`
`
`
`
`63—307270 12/1988 Japan .............
`.. 204/2982
`
`
`
`
`
`
`
`
`Primary Examiner—Aaron Weisstuch
`
`
`
`
`Attorney, Agent, or Firm—Wood, Herron & Evans
`
`
`ABSTRACT
`[57]
`
`
`
`
`
`
`
`
`A target of a thickness, which varies across its radius
`
`
`
`
`
`
`
`according to the amount of material required to be
`
`
`
`
`
`sputtered, is supported in a nest in a chamber of a sput-
`
`
`
`
`
`
`
`ter coating apparatus. Positioned behind the nest is a
`
`
`
`
`
`
`rotating magnet cam'er having arranged thereon in a
`
`
`
`
`
`
`closed loop a permanent or electro magnetic strip, but
`
`
`
`
`
`preferably a flexible permanently magnetic material,
`
`
`
`
`
`
`
`
`
`with portions near the rim of the target and portions
`
`
`
`
`
`
`
`
`
`
`near, but not on, the target center about which the
`
`
`
`
`
`
`magnet rotates. The magnetic loop is transversely po-
`
`
`
`
`
`
`
`
`
`
`larized with one pole toward the target rim and one
`
`
`
`
`
`
`
`
`
`toward the target center so that its field will enclose the
`
`
`
`
`
`
`
`
`rim of the target within a magnetic tunnel that traps a
`
`
`
`
`
`
`
`
`plasma over the target. Lumped magnets across the
`
`
`
`
`
`
`
`
`
`
`center from the strip support the plasma near the center
`
`
`
`
`
`
`
`
`so as to cause some sputtering at the target center.
`
`
`
`
`
`
`
`
`Other lumped magnets adjacent the strip help sharpen
`
`
`
`
`
`
`
`the field so that a desired distribution of sputtering can
`
`
`
`
`
`
`
`be achieved. Enclosed in a sealed space behind and in
`
`
`
`
`
`
`
`
`
`thermal contact with the target nest is the carrier from
`
`
`
`
`
`
`
`
`which the magnets project to facilitate the flow of cool-
`
`
`
`
`
`
`
`
`
`
`ing fluid across the back surface of the nest to cool the
`
`
`
`
`target as the carrier rotates.
`
`
`
`
`22 Claims, 5 Drawing Sheets
`
`
`
`
`
`Page 1 of 14
`
`APPLIED MATERIALS EXHIBIT 1072
`
`Page 1 of 14
`
`APPLIED MATERIALS EXHIBIT 1072
`
`

`

`
`US. Patent
`
`
`
`
`
`July 14, 1992
`
`
`
`
`
`Sheet 1 of 5
`
`5,130,005
`
`
`
`— ----—-—---—--_——~——-__—-
`
`
`'7
`
`A §§
`
`.
`
`
`QMJL.\x.\me
`
`
`.i,_§=====_.I_=______.___m”/,\.HWM§
`§.\.\\\w.§fsm“mM.“n“.
`3_R_m§__a,,am._
`.._.3EEmm2“:«J:
`
`..Em!\\\../.w..u"u.ru.\\.
`
`.kw.oxmlfluumw
`.vpAulll'l‘
`..oflflllra
`
`
`
`
`
`
`_.o_n_
`
`
`
`
`
`
`
`
`
`
`75
`
`_.\\\./. .\\\nH...
`
`/
`
`E:
`
`7"
`
`g \
`
`
`
`
`
`
`$vaWWI/V”an”.S\\\§V\\.V\\\\\\\\\m§mM‘\\\\.\\\\\\V\\\\\\\\\\\\"WW—IA“”5....”WV.x”mm._kwa“:..r.“\\\mn\
`
` \\\\\\uMWm.\mNmwm;.......JI.“........V\\knxx.1N/A.‘\\\\\\\xL1!?L:‘-l..1
`
`VVVVVVN.”«x.
`.A/,_V.\_Q.nwuu“w.IA"”ht.,..ll....mfi‘muwlm
`
`r,.WarmIMM,”lu!§V\\L‘\\\\N\\N\N.‘\m$\\\§fl&fi\§\bfi§hfifl%’”4..
`
`2._fl.2...“:x.m:”/7”
`
`Rex".f‘fmafiffm’gVIIEz
`xxV\I\\§\NW“Nfifi\
`
`
`5%
`
`$3
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`s,
`
`
`
`
`
`
`
`Page 2 of 14
`
`Page 2 of 14
`
`
`
`
`
`
`
`
`
`
`

`

`
`US. Patent
`
`
`
`
`
`July 14, 1992
`
`
`
`
`Sheet 2 of 5
`
`5,130,005
`
`
`
`
`
`
`
`Page 3 of 14
`
`Page 3 of 14
`
`

`

`US. Patent
`
`5,130,005
`
`___==____
`
` $§\\§\§§§
`3%? III"I
`
`
`
`Page 4 of 14
`
`
`

`

`
`U.S. Patent
`
`
`
`July 14, 1992
`
`
`
`
`
`Sheet 4 of 5
`
`
`‘
`
`5,130,005
`
`
`
`
`
`
`
`Page 5 of 14
`
`Page 5 of 14
`
`

`

`
`US. Patent
`
`
`
`
`
`July 14, 1992
`
`
`
`Sheet 5 of 5
`
`
`5,130,005
`
`
`
`
`
`
`
`Page 6 of 14
`
`Page 6 of 14
`
`

`

`1
`
`MAGNETRON SPUTI'ER COATING METHOD
`
`
`
`
`AND APPARATUS WITH ROTATING MAGNET
`
`
`
`
`
`CATHODE
`
`
`5,130,005
`
`
`
`
`
`
`
`
`
`
`
`
`2
`
`
`
`
`
`
`
`coated. Varying the relative parameters affecting the
`
`
`
`
`
`
`
`energization of the two target regions provides control
`
`
`
`
`
`
`
`of coating uniformity on the substrate surfaces, which is
`
`
`
`
`
`
`especially important on the differently facing surfaces
`
`
`
`
`
`
`of stepped semiconductor wafers. The aforereferenced
`
`
`
`
`
`
`patent application particularly describes effects on the
`
`
`
`
`
`
`
`
`coating caused by the target geometry and by the elec-
`
`
`
`
`
`
`
`
`trical parameters relating to the energization of the
`
`
`
`target and plasmas.
`
`
`
`
`
`
`
`
`In magnetron sputter coating processes, the sputter-
`
`
`
`
`
`
`
`
`ing of materials from the sputtering target occurs most
`
`
`
`
`
`
`
`
`
`rapidly into regions of the target where the plasma
`
`
`
`
`
`
`
`
`trapped by the magnetic field is the most dense. This
`
`
`
`
`
`causes a proportionate consumption or erosion of the
`
`
`
`
`
`
`
`
`sputtering material from the target surface. The erosion
`
`
`
`
`
`
`
`
`of sputtering material from other portions of the sput-
`
`
`
`
`
`
`
`tering target surface generally occurs at a rate which
`
`
`
`
`
`
`varies in proportion to the strength and/or duration of
`
`
`
`
`
`
`
`
`the plasma over that portion of the target surface.
`
`
`
`
`
`
`
`
`
`In the prior art it has been proposed in certain appli-
`
`
`
`
`
`
`
`
`
`cations to move the magnetic field in relation to the
`
`
`
`
`
`
`
`sputtering target surface either by movement of the
`
`
`
`
`
`target or movement of the magnetic field. A purpose of
`
`
`
`
`
`
`
`
`the relative movement of the target or magnetic field
`
`
`
`
`
`
`
`
`with respect to each other is, in many cases, to provide
`
`
`
`
`
`
`
`a more uniform erosion or consumption of the sputter-
`
`
`
`
`
`
`
`
`
`ing target material over the surface of the target. Such
`
`
`
`
`
`
`
`devices have for many reasons been unsatisfactory.
`
`
`
`
`
`
`
`In sputtering from a sputtering target while moving
`
`
`
`
`
`
`
`
`the target with respect to the magnetic field, a desirable
`
`
`
`
`
`
`erosion pattern is sometimes achieved for purposes of
`
`
`
`
`
`
`
`
`uniformly consuming the target material, but often such
`
`
`
`
`
`
`
`
`
`a pattern does not provide the proper or desired distri-
`
`
`
`
`
`
`
`
`bution of sputter coating material onto the surface of
`
`
`
`
`
`
`
`the substrate being coated. Furthermore, such devices
`
`
`
`
`
`
`
`
`
`of the prior art have insufficiently controlled the distri-
`
`
`
`
`
`
`
`
`
`bution of the plasma or the duration of the moving
`
`
`
`
`
`
`
`plasma with respect to the target surface so as to affect
`
`
`
`
`
`a desired non-uniform erosion pattern.
`
`
`
`
`
`
`
`
`In addition, rotating magnet devices of the prior art
`
`
`
`
`
`
`
`
`have not effectively provided for the sputtering of the
`
`
`
`
`
`
`
`
`
`entire surface of the target. It has been found that the
`
`
`
`
`
`
`
`absence of at least some sputtering from any given re-
`
`
`
`
`
`
`
`gion of the target may cause redeposition of the material
`
`
`
`
`
`
`
`
`sputtering from elsewhere on the target onto those
`
`
`
`
`
`
`regions where no sputtering is occurring. This causes a
`
`
`
`
`
`build-up of sputtering material which is undesirable.
`
`
`
`
`
`
`Accordingly, there is a need to provide a method and
`
`
`
`
`
`
`
`apparatus for sputter coating substrates which employs
`
`
`
`
`
`
`
`a magnet which is movable relative to the sputtering
`
`
`
`
`
`
`
`target and which is capable of precisely controlling the
`
`
`
`
`
`
`
`distribution of sputtering on the target surface in its
`
`entirety.
`
`
`
`
`
`
`
`When the magnet structure and target are rotated
`
`
`
`
`
`
`
`
`
`relative to each other, the prior art devices have failed
`
`
`
`
`
`
`
`
`to provide for sufficient sputtering from certain regions
`
`
`
`
`
`
`
`
`
`of the target surface, such as the center and edge re-
`
`
`
`
`
`
`
`gions of the target, and further have failed to effectively
`
`
`
`
`
`
`
`distribute the sputtering across the target surface in a
`
`
`
`
`
`
`
`manner which is effective to produce the desired ero-
`
`
`
`
`
`
`
`sion pattern to yield the proper coating uniformity on
`the substrate.
`
`
`SUMMARY OF THE INVENTION
`
`
`
`
`
`
`
`
`
`It is an objective of the present invention to provide
`
`
`
`
`
`
`
`a sputtering coating method and apparatus in which a
`
`
`
`
`
`
`magnet, positioned behind a sputtering target opposite
`
`
`
`
`
`
`
`the sputtering surface to generate a plasma trapping
`
`
`20
`
`
`
`
`
`
`
`
`This application is a continuation-in-part of US. pa~
`
`
`
`
`
`
`
`
`
`tent application Ser. No. 07/606,701, filed Oct. 31, 1990
`
`
`
`
`
`
`entitled “Magnetron Sputter Coating Apparatus with
`
`
`
`
`
`
`Rotating Cathode Magnet," now abandoned, which is a
`10
`
`
`
`
`
`patent
`continuation-in-part
`of US.
`application
`
`
`
`
`
`
`
`
`07/570,943, filed Aug. 22, 1990 entitled “Sputter Coat-
`
`
`
`
`
`
`
`ing Process Control Method and Apparatus," which is
`
`
`
`
`
`
`continuation-in-part of US. patent application Ser. No.
`
`
`
`
`
`
`
`
`07/339,308, filed Apr. 17, 1989 entitled “Method and
`15
`
`
`
`
`
`
`
`Apparatus for Sputter Coating Stepped Wafers," now
`US. Pat. No. 4,957,605.
`
`
`
`
`FIELD OF THE INVENTION
`
`
`
`
`
`
`
`
`
`The present invention relates to sputter coating and
`
`
`
`
`
`more particularly to magnetron enhanced sputter coat-
`
`
`
`
`
`
`ing processes and apparatus employing magnets which
`
`
`
`
`
`
`- are movable with respect to a sputtering cathode target.
`BACKGROUND OF THE INVENTION
`
`
`
`25
`
`
`
`
`
`
`Sputter coating is a process carried out in a vacuum
`
`
`
`
`
`
`chamber which is filled with a generally chemically
`
`
`
`
`
`
`
`inert gas in which a substrate is coated with a material
`
`
`
`
`
`
`from a target of sputtering material subjected to a nega-
`
`
`
`
`
`
`
`
`tive electrical potential with respect to the chamber
`
`
`
`
`
`
`
`
`wall or other anode. The potential gradient adjacent the
`
`
`
`
`
`
`
`target surface causes electrons to be emitted from the
`
`
`
`
`
`
`
`
`target which, on their way to the chamber anode which
`
`
`
`
`
`
`
`is usually formed in part by the grounded chamber wall,
`
`
`
`
`
`
`
`
`
`
`strike and ionize some of the inert gas. The positive ions
`35
`
`
`
`
`
`
`
`
`formed are then attracted to the negative target which
`
`
`
`
`
`
`
`they strike, transferring momentum to the target mate-
`
`
`
`
`
`
`
`
`
`rial. and ejecting particles of the material from the tar-
`
`
`
`
`
`
`
`get surface. The substrate to be coated, which is posi-
`
`
`
`
`
`
`
`
`tioned in the chamber usually with its surface facing the
`
`
`
`
`
`
`
`target, receives some of the ejected particles which
`adhere to and coat the substrate surface.
`
`
`
`
`
`
`
`
`
`
`
`
`With magnetron sputtering, a magnetic field is
`
`
`
`
`
`
`
`
`formed over the target surface, usually including mag—
`
`
`
`
`
`
`
`
`
`netic field lines parallel to the target surface, and, in
`45
`
`
`
`
`
`
`many applications,
`in the form of a closed magnetic
`
`
`
`
`
`
`
`
`tunnel. The magnetic field causes the electrons emitted
`
`
`
`
`
`
`
`
`
`to move in curved spiral paths which trap them in re-
`
`
`
`
`
`
`
`gions proximate the target surface enclosed by the field,
`
`
`
`
`
`
`
`
`thereby increasing the rate of electron collisions with
`
`
`
`
`
`
`
`
`gas atoms, which in turn increase the ionization of the
`
`
`
`
`
`
`
`gas and the efficiency of the sputtering process.
`
`
`
`
`
`
`
`
`In the commonly assigned and copending US. patent
`
`
`
`
`
`
`
`
`application Ser. No. 07/339,308, filed Apr. 17, 1989,
`
`
`
`
`
`
`
`entitled “Method and Apparatus for Sputter Coating
`55
`
`
`
`
`
`
`
`
`Stepped Wafers", now US. Pat. No. 4,957,605, ex-
`
`
`
`
`
`
`pressly incorporated herein by reference, a sputter coat-
`
`
`
`
`
`
`
`
`ing apparatus and method are disclosed in which a con-
`
`
`
`
`
`
`
`cave annular target is provided with concentric annular
`
`
`
`
`
`
`electromagnets which cause the formation of a pair of
`60
`
`
`
`
`
`
`
`
`concentric plasma rings. The plasma rings are alter-
`
`
`
`
`
`
`
`nately energized by alternately supplying current to
`
`
`
`
`
`
`
`
`
`energize the magnet coils while the target power level
`
`
`
`
`
`
`
`is switched in synchronization with the switching of the
`
`
`
`
`
`
`
`
`current to the magnetic coils. This causes different rates
`65
`
`
`
`
`
`
`
`
`of sputtering from inner and outer concentric regions of
`
`
`
`
`
`
`
`
`
`the target surface, with the sputtering from each region
`
`
`
`
`
`
`causing different distribution characteristics of the sput-
`
`
`
`
`
`
`
`tered material deposited on the substrate or wafer being
`
`
`
`
`
`
`
`Page 7 of 14
`
`Page 7 of 14
`
`

`

`5,130,005
`
`IO
`
`
`
`
`3
`
`
`
`
`
`
`
`
`closed magnetic field or tunnel over the sputtering tar-
`
`
`
`
`
`
`get surface,
`is shaped and rotated so as to produce a
`
`
`
`
`
`
`
`desired average sputtering distribution across the sur-
`
`
`
`face of the target.
`
`
`
`
`
`
`
`It is a more particular objective of the present inven—
`
`
`
`
`
`
`tion to provide a rotating magnet magnetron sputtering
`
`
`
`
`
`
`
`apparatus that avoids unsputtered areas of the target,
`
`
`
`
`
`
`and thus avoids a buildup by redeposition of sputtered
`
`
`
`material on the target.
`
`
`
`
`
`
`
`
`
`It is another objective of the present invention to
`
`
`
`
`
`
`provide a rotating magnet sputtering target apparatus
`
`
`
`
`
`
`
`and method having a magnet structure which is con-
`
`
`
`
`
`
`figurable to produce a desired coating deposition on the
`
`
`
`
`
`
`
`substrate when the magnet structure is rotated during
`
`sputtering.
`
`
`
`
`
`
`
`It is a further objective of the present invention to
`
`
`
`
`
`
`
`provide the rotating magnet structure in a sputter coat-
`
`
`
`
`
`
`
`ing apparatus wherein the rotating magnet structure
`
`
`
`
`
`
`
`
`facilitates the circulation of cooling fluid for the sputter-
`
`
`
`ing cathode assembly.
`
`
`
`
`
`
`According to the principles of the present invention
`
`
`
`
`
`
`there is provided a sputter coating apparatus having a
`
`
`
`
`
`
`sputtering target included in a cathode assembly with a
`
`
`
`
`
`
`
`
`magnet located behind the sputtering target so as to
`
`
`
`
`
`
`
`
`produce a closed magnetic field over the target surface.
`
`
`
`
`
`
`
`The magnet is rotatably mounted so as to rotate the
`
`
`
`
`
`
`
`
`magnetic field over the surface of the sputtering target.
`
`
`
`
`
`
`
`The magnet is configured with respect to the target to
`
`
`
`
`
`
`
`
`
`cause sputtering from the center of the target to the
`
`
`
`
`
`
`
`
`
`outer rim of the target at a rate which varies with the
`radius from the center in a desired manner.
`
`
`
`
`
`
`
`
`
`
`
`
`
`In the preferred and illustrated embodiment of the
`
`
`
`
`
`
`present invention, the magnet is preferably a permanent
`
`
`
`
`
`
`
`magnet which includes a closed loop of magnetic mate-
`35
`
`
`
`
`
`
`
`
`rial formed of a flexible magnetic strip. The strip has its
`
`
`
`
`
`
`
`poles spaced transversely across the strip, preferably
`
`
`
`
`
`
`
`
`
`generally in the plane in which the closed loop lies. The
`
`
`
`
`
`
`magnet, which is formed of flexible laminated strips of
`
`
`
`
`
`magnet impregnated plastic,
`is arranged on a rotating
`40
`
`
`
`
`
`
`
`plate behind the sputtering target in a shape having a
`
`
`
`
`
`
`plurality of curves including a plurality of outwardly
`
`
`
`
`
`
`
`
`
`convex curves, some near the outer rim of the target,
`
`
`
`
`
`
`
`
`
`
`and at least one point at which the strip passes near, but
`
`
`
`
`
`
`
`
`not through, the target center. The magnet is shaped in
`45
`
`
`
`
`
`
`
`
`such a way that the plasma trapped by the magnetic
`
`
`
`
`
`
`
`
`field will be present over various portions of the sput-
`
`
`
`
`
`
`
`
`
`tering target at various radii from the center for prede-
`
`
`
`
`
`termined amounts of time so as to provide a desired
`
`
`
`
`
`erosion pattern on the target surface.
`
`
`
`
`
`
`According to the preferred embodiment of the pres-
`
`
`
`
`
`
`
`
`ent invention, the magnet is polarized in such a way that
`
`
`
`
`
`
`
`
`
`one pole faces the outer edge of the rotating plate while
`
`
`
`
`
`
`
`
`
`the other pole faces the axis of rotation so that, particu-
`
`
`
`
`
`
`
`
`
`
`la.rly at the outer edge, the field emerges from the mag-
`55
`
`
`
`
`
`
`
`
`
`net and surrounds the outer rim of the target to facilitate
`
`
`
`
`
`
`
`
`
`sputtering from the target rim, without the rieecl to
`
`
`
`
`
`
`provide an enlarged magnet structure extending beyond
`
`
`
`
`the target outer rim.
`
`
`
`
`
`In addition, according to a preferred embodiment of
`60
`
`
`
`
`
`
`
`the present invention, fixed lumped magnets of different
`
`
`
`
`
`
`
`magnetic material are positioned at various points along
`
`
`
`
`
`
`the magnetic loop so as to selectively influence portions
`
`
`
`
`
`
`
`
`
`of the magnetic field to provide certain desired field
`
`
`
`
`
`
`shapes. Particularly, according to certain preferred
`65
`
`
`
`
`
`
`
`embodiments of the present invention, the lumped mag-
`
`
`
`
`
`
`
`
`
`
`nets are oriented with one pole toward the target and
`
`
`
`
`
`
`
`
`
`one away from the target so that the magnetic fields
`
`
`
`
`
`
`
`produced by the lumped magnets cooperate with the
`
`
`
`4
`
`
`
`
`
`
`
`field provided by the magnetic loop to sharpen the field
`
`
`
`
`
`
`
`
`at various points. Particularly, certain of the lumped
`
`
`
`
`
`
`
`
`magnets are provided opposite the axis of rotation from
`
`
`
`
`
`
`
`
`
`
`the point of the loop where the magnet most closely
`
`
`
`
`
`
`
`
`
`approaches the axis. In this way, a small portion of the
`
`
`
`
`
`
`
`
`magnetic field, which does not otherwise extend across
`
`
`
`
`
`
`
`
`
`the central portion of the target, is drawn across the
`
`
`
`
`
`
`
`
`center to provide some degree of erosion to, and sput—
`
`
`
`
`
`
`
`
`
`
`tering from, the central portion of the target. In addi-
`in accordance with certain embodiments of the
`tion,
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`present invention, the lumped magnets are provided at
`
`
`
`
`
`
`
`
`
`the outermost reaches of the loop near the edge of the
`
`
`
`
`
`
`
`
`target to shape the field more precisely in these regions.
`
`
`
`
`
`
`
`In accordance with further objectives of the present
`
`
`
`
`
`
`
`invention, the target itself is shaped in a way to cooper-
`
`
`
`
`
`
`
`
`ate with the sputtering pattern created by the magnetic
`
`
`
`
`
`configuration so as to provide for a maximum utilization
`
`
`
`
`
`
`
`
`
`
`of the target material. In this respect, the target is of
`
`
`
`
`
`
`
`non-uniform thickness and is, for example, in the illus-
`
`
`
`
`
`
`
`trated embodiment, more particularly thicker at
`the
`
`
`
`
`
`
`
`outer regions near the outer edge thereof.
`
`
`
`
`
`
`In alternative embodiments, particularly where there
`
`
`
`
`
`
`
`may be some advantage to varying or adjusting the
`
`
`
`
`
`
`
`
`magnetic field strength, any of the magnets, and particc
`
`
`
`
`
`
`
`ularly the closed loop magnet, may be electromagnets.
`
`
`
`
`
`
`
`In accordance with further objectives of the present
`
`
`
`
`
`
`invention, the target is bonded or otherwise secured in
`
`
`
`
`
`
`
`intimate heat conducting contact with a target nest. A
`
`
`
`
`
`
`
`
`closed cavity is provided behind the target nest enclos-
`
`
`
`
`
`
`
`ing the rotating magnet. A turbulent layer of water or
`
`
`
`
`
`
`other cooling fluid is maintained by injecting cooling
`
`
`
`
`
`
`
`
`
`
`water into the cavity behind the nest. The fluid is in~
`
`
`
`
`
`
`
`
`
`jected into the space near the center of the target assem-
`
`
`
`
`
`
`
`
`bly near the axis of rotation of the magnet so as to flow
`
`
`
`
`
`
`
`through a narrow space between the rotating magnet
`
`
`
`
`
`
`
`
`
`
`and the back surface of the target nest. In this space, the
`
`
`
`
`
`
`
`
`cooling fluid is propelled along the back surface of the
`
`
`
`
`
`
`
`nest and outwardly by the rotation of the magnet struc-
`
`
`
`
`
`
`
`
`ture, and more particularly by the raised surface of the
`
`
`
`
`
`magnets themselves, so as to provide a turbulent skin of
`
`
`
`
`
`
`
`
`cooling water adjacent the surface of the nest improv-
`
`
`
`
`
`
`
`ing the flow of the water and the
`
`
`
`
`
`
`
`
`These and other objectives and advantages of the
`
`
`
`
`
`
`
`present invention will be more readily apparent from
`
`
`
`
`
`
`
`the following detailed description of the drawings in
`which:
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`
`
`
`
`
`
`
`
`FIG. 1 is a cross-sectional view through a target
`
`
`
`
`
`assembly of one preferred embodiment of an apparatus
`
`
`
`
`
`embodying principles of the present invention.
`
`
`
`
`
`
`
`FIG. 2 is a view taken generally along lines 2—2 of
`
`
`
`
`
`
`
`
`
`FIG. 1 illustrating the face of the rotatable plate and
`
`
`magnet assembly.
`
`
`
`
`
`
`FIG. 3 is a cross-sectional view along lines 3—3 of
`FIG. 2.
`
`
`
`
`
`
`FIG. 4 is a fragmentary cross-sectional View along
`lines 4—4 of FIG. 2.
`
`
`
`
`
`
`
`
`
`
`FIG. 5 is a view similar to FIG. 2 illustrating an
`
`
`
`
`
`alternative rotating magnet assembly configuration.
`
`
`
`
`
`FIG. 6 is a set of diagrams A through D illustrating
`
`
`
`
`
`
`
`
`the preferred magnetic pole orientation for the main
`
`
`
`
`
`
`
`magnet according to certain features of the present
`invention.
`
`
`
`
`
`
`FIG. 7 is a set of diagrams A through D illustrating a
`
`
`
`
`
`preferred auxiliary magnetic arrangement according to
`
`
`
`
`
`certain features of the present invention.
`
`15
`
`
`
`20
`
`
`
`25
`
`
`
`30
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Page 8 of 14
`
`Page 8 of 14
`
`

`

`5,130,005
`
`10
`
`
`
`15
`
`
`
`
`
`
`
`
`
`35
`
`
`
`
`
`
`
`.
`6
`
`
`
`
`
`
`
`
`the above incorporated U.S. Pat. Nos. 4,909,675 and
`4,915,564.
`
`
`
`
`
`
`
`
`In this preferred embodiment, the wafer 21 is sup-
`
`
`
`
`
`
`ported in a plane perpendicular to, and concentric with,
`
`
`
`
`
`
`
`
`a central axis 27 of the main chamber 10, which is also
`
`
`
`
`
`
`
`
`
`concentric with the hole 15 in the plenum wall 14. Sur~
`
`
`
`
`
`
`
`
`rounding the wafer 21 on the holder 25 is a disk 29
`
`
`
`
`
`
`
`which at least partially protects the holder 25 from an
`
`
`
`
`
`
`
`excessive accumulation of coating intended for but
`which missed, the surface 22 of the wafer 21. Details of
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`the sputtering apparatus of which the processing cham-
`
`
`
`
`
`
`
`ber 10 is a part including particularly details of the
`
`
`
`
`
`
`
`
`wafer transport 17, wafer holder 25, and backplane
`section 16, are described and illustrated in U.S. Pat.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Nos. 4,909,695 and 4,915,564 incorporated by reference
`above.
`'
`
`
`
`
`
`
`
`
`The cathode assembly module 20 includes two assem-
`
`
`
`
`
`
`
`blies, a removable cathode assembly 30 and a fixed
`
`
`
`
`
`
`
`assembly portion 31. The fixed assembly portion 31 is an
`
`
`
`
`
`
`annular enclosure rigidly mounted in sealed relationship
`
`
`
`
`
`
`
`against the plenum wall 14 surrounding the opening 15.
`
`
`
`
`
`
`
`
`It includes a cylindrical metal side wall 33 of the cham-
`
`
`
`
`
`
`ber 10. which is electrically grounded to the frame 14 of
`
`
`
`
`
`
`
`
`the plenum, a wafer holder shield 34 which surrounds
`
`
`
`
`
`
`
`
`the opening 15 and a chamber door frame assembly 35.
`
`
`
`
`
`
`The cathode assembly 30 is mounted to a hinged door
`
`
`
`
`
`
`
`assembly 37 which removably but sealably supports the
`
`
`
`
`
`
`
`
`cathode assembly 30 to the fixed assembly 31. The cath—
`
`
`
`
`
`
`
`
`ode assembly 30 carries the sputtering target 40, which
`
`
`
`
`
`
`
`is a circular target having a continuous smooth concave
`
`
`
`
`
`
`
`
`sputtering surface 41 and a back surface 39. The assem-
`
`
`
`
`
`
`
`bly 30 supports the target 40 with its axis in alignment
`
`
`
`
`
`
`
`
`with the axis 27 of the chamber 10 and with its sputter-
`
`
`
`
`
`
`
`ing surface 41 facing the surface 22 of the wafer 21 to be
`coated.
`
`
`
`
`
`
`
`The target 40 is supported in a target nest 42 having
`
`
`
`
`
`
`
`a front surface 43 conforming to surface 39 and concen-
`
`
`
`
`
`
`
`
`
`tric with axis 27. The back surface 39 of the target 40 is
`soldered or otherwise bonded to the front surface 43 of
`
`
`
`
`
`
`the nest 42, in intimate thermal contact therewith. The
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`target back surface 39 is a cooling surface which, when
`the target 40 is mounted in holder 42, conforms to and
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`lies in close cooling contact with the surface 43 of the
`
`
`
`
`
`
`
`
`
`holder 42. Behind the nest 42, opposite the cooling
`
`
`
`
`
`
`
`surface 43 thereof, is a space 44 for the circulation of
`
`
`
`
`
`
`
`cooling liquid, which is generally water, to remove heat
`
`
`
`
`
`
`generated in the target 40 during sputtering by cooling
`
`
`
`
`
`
`
`
`
`the heat conductive target holder 42. The cooling fluid
`
`
`
`
`
`
`
`
`
`is circulated into and out of the space 44 from an inlet
`
`
`
`
`
`
`port 45 to an outlet port 46 in a magnet assembly 50, as
`
`
`
`
`
`
`
`described below. The space 44 is enclosed behind the
`nest 42 by a housing structure 48 onto which the nest 42
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`is rigidly supported, and to which it is secured by bolts
`49.
`
`
`
`
`
`
`
`
`The shapes of the surfaces of the target 40 are prefer-
`
`
`
`
`
`
`
`
`
`
`ably such that all
`the target 40 is capable of being
`
`
`
`
`
`formed by turning a block of sputtering material on a
`
`
`
`
`
`
`
`lathe. The target holder 40 is made of a heat conductive
`
`
`
`
`
`
`and electrically conductive material, preferably hard
`
`
`
`
`
`tempered OFHC copper or Alloy 110.
`
`
`
`
`
`
`The magnet assembly 50 includes a shaft 51 having a
`
`
`
`
`
`
`
`
`
`threaded end 52 by which the shaft 51 is rigidly
`mounted in a threaded bore 53 at the center of the back
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`surface of the nest 42. The assembly 50 also includes a
`
`
`
`
`
`
`rotatable magnet carrier assembly 55 which includes a
`
`
`
`
`
`
`circular disk 56 of non-magnetic stainless steel or other
`such material having a central hole 57 therein at which
`
`
`
`
`
`
`
`
`
`
`
`
`
`the disk 56 is rigidly mounted to a sleeve assembly 58
`
`3O
`
`
`5
`
`
`
`
`
`FIG. 8 is a set of diagrams A and B illustrating a
`
`
`
`
`
`preferred auxiliary magnetic arrangement according to
`
`
`
`
`
`other features of the present invention.
`DETAILED DESCRIPTION OF DRAWINGS
`
`
`
`
`
`
`
`
`
`Magnetron sputtering devices of the type to which
`
`
`
`
`
`
`
`
`the present invention relates are described in the follow-
`
`
`
`
`
`
`
`ing commonly assigned U.S. patents and copending
`
`
`
`
`
`
`
`patent applications which are hereby expressly incorpo-
`
`
`
`
`
`
`
`rated in their entirety into this application by reference:
`U.S. Pat. Nos. 4,909,695 and 4,9l5,564 entitled
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`"Method and Apparatus for Handling and Processing
`Wafer-Like Materials"; and,
`
`
`
`
`
`
`
`
`
`
`U.S. patent application Ser. No. 07/339,308, filed
`
`
`
`
`
`
`
`
`
`Apr. 17, 1989, now U.S. Pat. No. 4,957,605, entitled
`
`
`
`
`
`
`
`"Method and Apparatus for Sputter Coating Stepped
`Wafers.”
`
`
`
`
`
`
`
`FIG. 1 illustrates, in cross-section, a sputter coating
`
`
`
`
`
`processing chamber 10 of a sputter coating apparatus
`20
`
`
`
`
`
`
`according to principles of the present invention. The
`
`
`
`
`
`chamber 10 is a portion of the sputter processing appa-
`
`
`
`
`
`
`
`
`ratus disclosed in U.S. Pat. No. 4,909,695. The process
`
`
`
`
`
`
`ing chamber 10 is a vacuum processing chamber fCirmed
`of an isolated section of a main chamber 11. The main
`
`
`
`
`
`
`
`25
`
`
`
`
`
`
`chamber 11 is isolated from the atmosphere of the ma-
`
`
`
`
`
`
`
`chine. environment 12 by a plenum wall 14. The pro-
`
`
`
`
`
`cessing chamber 10 is capable of communicating with
`
`
`
`
`
`
`the main chamber 11 throughout opening 15 (shown
`
`
`
`
`
`sealed) in the plenum wall 14.
`
`
`
`
`
`
`
`
`As more fully described in U.S. Pat. No. 4,909,695,
`
`
`
`
`
`
`
`the sealing of the opening 15 isolates the chamber 10
`
`
`
`
`
`
`
`from the main processing chamber 11 by the selective
`
`
`
`
`
`movement of a processing chamber backplane section
`
`
`
`
`
`
`
`
`16 against a portion of a disk shaped rotary wafer trans-
`
`
`
`
`
`
`port member 17 clamping the transport member 17
`
`
`
`
`
`
`
`
`between the backplane section 16 and the plenum wall
`
`
`
`
`
`
`
`14 in a sealing relationship (as shown), thereby enclos~
`
`
`
`
`
`
`
`ing a backplane space 19 within the processing chamber
`
`
`
`
`
`
`
`
`10 and isolating the processing chamber 10 from the
`main chamber 11.
`
`
`
`
`
`
`
`
`
`
`Opposite the backplane section 16, on the front plane
`
`
`
`
`
`
`
`side of the transport member 17, the processing cham-
`ber 10 is isolated from the machine environment 12 with
`
`
`
`
`
`
`
`45
`a cathode assembly module 20 mounted in a vacuum
`
`
`
`
`
`
`
`
`
`
`
`
`
`sealing relationship against the plenum wall 14 surround
`
`
`
`
`
`
`
`
`the opening 15. The module 20, or processing chamber
`
`
`
`
`
`
`
`frontplane section, cooperates with the backplane sec-
`
`
`
`
`
`
`
`
`tion 16 and the transport member 17 to form the sealed
`
`
`
`
`
`
`
`isolated processing chamber which is isolated from both
`the main chamber 11 and the machine external environ-
`
`
`
`
`
`
`
`
`ment 12.
`
`
`
`
`
`
`
`Within the processing chamber 10 is a substrate or
`
`
`
`
`
`
`
`workpiece 21 in the form of a flat silicon wafer or disk
`
`
`
`
`
`
`
`which has the surface 22 upon which a coating is to be
`
`
`
`
`
`deposited in a sputter coating process to be performed
`
`
`
`
`
`
`
`within the processing chamber 10. The wafer 21 is held
`
`
`
`
`
`
`
`by a set of clips or other retaining devices 24 in a wafer
`
`
`
`
`
`
`holder 25 resiliently carried by the transport member
`
`
`
`
`
`